Here is a real life example -
A small unit in a state DMV was, by law, self-funded via fees charged to municipalities for their services. By law, they had to be revenue-neutral - just charge for their costs.
How laws get applied by government are usually defined and interpreted through "administrative rules" - which lays out the details of what the department thinks it means and how that translates into real-life action.
The administrative rules stated that this unit shall recalculate their per case fees on an annual basis, based on past costs and trends in caseloads.
It reached the point where, one year, the per case cost was $5.00. The municipality customers for that unit really liked that nice, round, easy to work with figure and the feedback was that they'd be fine keeping it there (they passed those costs on to the citizens involved, anyway) as opposed to an adjustment to $4.93, if it represented a minor savings for them.
The department drafted a revised administrative rule saying that it may recalculate the fees on an annual basis. So, if costs were changing in any substantive way, or if the unit needed to slightly increase to keep from running at deficit, they could recalculate, but no more often than yearly. Previously, they had to recalculate yearly, every year. This change had to be approved by the state legislature, but something that minor really didn't receive much scrutiny, but did represent a bit of a departure from the pure intent of the law, as originally written and interpreted.